gpio: omap: clear level bits when switching to edge detect in idle

The gpio controller in omap4 can only wake from idle on edge
triggered lines.  The level triggered interrupts are converted
to edge triggered in idle.  It appears that the edge triggered
enable bits are ignored if the level triggered bit is also set,
so clear the level trigger bit in idle and restore it later.

If a level triggered interrupt is pending when the level detect
register is cleared the edge detect setting will not detect it,
and the interrupt will be lost.  After clearing the level detect
bits, manually check the datain register against the saved
level detect values, and abort the transition if the interrupt
is pending.

Change-Id: I43fbee728cb6ebc407b8c4430a1cd37165354dc6
Signed-off-by: Colin Cross <ccross@android.com>

1 files changed, 42 insertions, 13 deletions

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index 26a5a7e..8fff8e1 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -1385,21 +1385,21 @@ static int omap_gpio_pm_runtime_resume(struct device *dev)
 }
 
 #ifdef CONFIG_ARCH_OMAP2PLUS
-static void omap2_gpio_set_edge_wakeup(struct gpio_bank *bank)
+static int omap2_gpio_set_edge_wakeup(struct gpio_bank *bank)
 {
-	u32 level_low = 0;
-	u32 level_high = 0;
+	int ret = 0;
 	u32 wkup_status = 0;
+	u32 datain;
 
 	if (pm_runtime_get_sync(bank->dev) < 0) {
 		dev_err(bank->dev, "%s: GPIO bank %d pm_runtime_get_sync "
 				"failed\n", __func__, bank->id);
-		return;
+		return -EINVAL;
 	}
 
-	level_low = __raw_readl(bank->base +
+	bank->context.leveldetect0 = __raw_readl(bank->base +
 			bank->regs->leveldetect0);
-	level_high = __raw_readl(bank->base +
+	bank->context.leveldetect1 = __raw_readl(bank->base +
 			bank->regs->leveldetect1);
 	wkup_status = __raw_readl(bank->base +
 			bank->regs->wkup_status);
@@ -1413,16 +1413,34 @@ static void omap2_gpio_set_edge_wakeup(struct gpio_bank *bank)
 	 * expected to produce wakeup from low power.
 	 * even if they are set for level detection only.
 	 */
-	__raw_writel(bank->context.edge_falling | (level_low & wkup_status),
-			(bank->base + bank->regs->fallingdetect));
-	__raw_writel(bank->context.edge_rising | (level_high & wkup_status),
-			(bank->base + bank->regs->risingdetect));
+	__raw_writel(bank->context.edge_falling |
+			(bank->context.leveldetect0 & wkup_status),
+		(bank->base + bank->regs->fallingdetect));
+	__raw_writel(bank->context.edge_rising |
+			(bank->context.leveldetect1 & wkup_status),
+		(bank->base + bank->regs->risingdetect));
+	__raw_writel(0, bank->base + bank->regs->leveldetect0);
+	__raw_writel(0, bank->base + bank->regs->leveldetect1);
+
+	/*
+	 * If a level interrupt is pending it will be lost since
+	 * we just cleared it's enable bit.  Detect and abort,
+	 * the interrupt will be delivered when
+	 * omap2_gpio_restore_edge_wakeup restores the level
+	 * interrupt mask.
+	 */
+	datain = __raw_readl(bank->base + bank->regs->datain);
+	if ((datain & bank->context.leveldetect1) ||
+	    (~datain & bank->context.leveldetect0))
+		ret = -EBUSY;
 
 	if (pm_runtime_put_sync_suspend(bank->dev) < 0) {
 		dev_err(bank->dev, "%s: GPIO bank %d pm_runtime_put_sync "
 				"failed\n", __func__, bank->id);
-		return;
+		return -EINVAL;
 	}
+
+	return ret;
 }
 
 static void omap2_gpio_restore_edge_wakeup(struct gpio_bank *bank)
@@ -1437,6 +1455,10 @@ static void omap2_gpio_restore_edge_wakeup(struct gpio_bank *bank)
 			(bank->base + bank->regs->fallingdetect));
 	__raw_writel(bank->context.edge_rising,
 			(bank->base + bank->regs->risingdetect));
+	__raw_writel(bank->context.leveldetect0,
+			(bank->base + bank->regs->leveldetect0));
+	__raw_writel(bank->context.leveldetect1,
+			(bank->base + bank->regs->leveldetect1));
 
 	if (pm_runtime_put_sync_suspend(bank->dev) < 0) {
 		dev_err(bank->dev, "%s: GPIO bank %d pm_runtime_put_sync "
@@ -1445,13 +1467,15 @@ static void omap2_gpio_restore_edge_wakeup(struct gpio_bank *bank)
 	}
 }
 
-void omap2_gpio_prepare_for_idle(int off_mode)
+int omap2_gpio_prepare_for_idle(int off_mode)
 {
+	int ret = 0;
 	struct gpio_bank *bank;
 
 	list_for_each_entry(bank, &omap_gpio_list, node) {
 		if (!bank->mod_usage || !bank->loses_context || !off_mode) {
-			omap2_gpio_set_edge_wakeup(bank);
+			if (omap2_gpio_set_edge_wakeup(bank))
+				ret = -EBUSY;
 			continue;
 		}
 
@@ -1460,6 +1484,11 @@ void omap2_gpio_prepare_for_idle(int off_mode)
 					"pm_runtime_put_sync failed\n",
 					__func__, bank->id);
 	}
+
+	if (ret)
+		omap2_gpio_resume_after_idle(off_mode);
+
+	return ret;
 }
 
 void omap2_gpio_resume_after_idle(int off_mode)